When the ability holder is switched out of battle, 1/3 of their HP is recovered. When a Pokémon gains the ability through Trace and similar, it will regain the health upon switching out if it isn't suppressed beforehand. Heal Block does not prevent healing from this ability.
The ability heals 20% of the Pokémon's max HP when changing floors.
Pokémon with the Ability
As a Hidden Ability